Signal Transduction Flashcards
(36 cards)
What is an agonist
Drug that binds to receptor and initiate specific reaction that results to biological response
Another name for second messengers
Effector molecules
What affects the magnitude of cellular response?
Number of drug receptor complex
They form a direct proportion
Give an example of drug that doesn’t act on receptor
Antacid: dissolves in stomach acid reducing stomach upset
The two receptor states are
Active and inactive states
How does agonist binding affect equilibrium between receptor states
It shifts the equilibrium from the inactive to active state to produce biologic effect
How does antagonist affect equilibrium of receptor states
It has no effect on the equilibrium.
It stabilizes the inactive state
Partial agonists effect on receptor state
It doesn’t completely shift the equilibrium to the active state.
A minimum percent of active state is gotten compared to the full agonist
What is a receptor
It is a biological molecule to which drug binds and produce measurable response.
Receptors could be;
Enzymes,
Structural proteins,
Nucleic acids
The richest source of receptors are
Transembranous proteins.
They transduce extracellular signals into intracellular responses.
List the four families of receptors
Ligand gated
Enzyme-linked receptors
Intracellular receptors
G- protein coupled receptor.
Where does hydrophobic and hydrophilic ligands interact with receptors
Receptors within the cell -hydrophobic
Receptors on the membrane -hydrophilic
Ligand gated Chanel activation
1) agonist binds on domain site.
2) open up the ion channel for influx of specific ion.
3) Fxn of the receptor differ in type of ions that are influxed
Two main function of ligand gated receptor
Neurotransmission and Muscle Contraction.
Neurotransmission: ACH activates nicotinic receptor.
> There’s influx of Na+ or K+ changing ionic concentration across membrane (A.P)
In neurons.
> Contraction in muscles
Effect of agonist on GABA receptor
Stimulates chloride influx leading to hyperpolarization of neurons.
This decrease Action potential generation.
How does local Anesthesia agonist work
They bind to voltage gated sodium channels, inhibiting sodium influx and decreasing neuronal conduction.
G protein receptor are in three forms
Gq , Gs and Gi
Configuration of G-protein subunit;
Alpha subunit binds to GTP/GDP
Beta and gamma subunit anchors the g protein to the cell membrane
Ligand gated ion channels open in how many seconds
Milliseconds
Responses from G-protein coupled receptor last for how long?
It lasts from several seconds to minutes
Second messengers are also known as what?
Activated effectors
Types of g proteins and effectors they activate or inhibit
Gs- activates Adenylyl cyclase
Gi- inhibits Adenylyl cyclase.
Gq- activates phospholipase C
How does enzyme linked receptor work
Using insulin receptor as case study;
Insulin receptor has tyrosine kinase at the Beta intracellular end.
When insulin binds;
>Tyrosine kinase autophosphorylate to get activated
>activated Tyrosine kinase activates insuline receptor substrates.
>Multissignalling pathway are activated.
> Insulin receptor substrates Futher phosphorylates other protein kinasesz phosphatases.
> This leads to biological effects of insulin
